As competition in the telecommunications market continues to grow, new ways are being sought to deliver telecommunications services, for example, Internet access to users. One way that is attractive for the power supply utilities is to deliver telecommunications services over power lines at frequencies over 1 MHz. Buried cable and short overhead drops are capable of carrying signals at these frequencies, but a major problem is wiring in the home. Such wiring is neither shielded nor twisted and is mainly above ground. It is thus a major source of interference, particularly at the frequencies used for shortwave broadcast, amateur radio, and airborne navigation. A filter is needed at the point of entry into the home. Given the huge difference in frequency between the power line, 60Hz and the signal, greater than 1 MHz, it would appear at first sight that it should not be difficult to construct such a filter. The problem arises from the fact that the low pass filter, carrying the power supply, has to carry huge currents, up to 200 Amperes, so that to avoid saturation the core would have to be physically enormous. Given the second order relationship between heat and current, any small resistive load in the filter will translate in the generation of a large amount of heat that not only has to be dissipated, but also wastes energy.